A removable dental appliance which comprises one or more artificial teeth, an acrylic holding means for the artificial teeth and a metal partial casting which acts as a base member for the artificial teeth is well known in dentistry. It is used to replace teeth which have been lost as a result of age or accident. The metal partial casting provides a means of holding the dental appliance securely in the mouth anchoring it on the remaining natural teeth by means of retentive clasping. But conventional clasping does not always supply the required retention. Extraordinary means must then be used. To be removable it must also contain a clasp or locking means. That clasp or locking means and the way that it is made is the concern of the present invention.
Generally the partial casting is made first on a refractory model which supports a partial wax pattern shaped exactly like the metal partial casting. Currently the locking clasp must be incorporated in the partial casting after the main portion of the partial casting has been cast. Thus two or more separate castings are required involving comparatively more time and labor. Also it is difficult to adjust some current locking clasps which are essentially a simple latch which, when they are made, can be misaligned so that they are difficult to open and close. Also some current locking clasps are comparatively weak.
Furthermore current procedures for making a partial casting with a locking clasp require that wax members be positioned in very close proximity to each other, keeping them separated with critical space tolerances necessary to their proper function. Quite often these spaces are bridged due to investment breakdown. This flawed joining of the wax members necessitates that a carbide burr be employed to remove the obstruction so that the two parts of the locking clasp can be separated. Also it is possible for the maker to misjudge the amount or degree of retention needed to have a properly working locking clasp. If there is a misjudgment at this critical step and too much retention results, then the locking clasp can not be opened and a carbide burr must be used to reduce the excess metal. Thus substantial reworking with a carbide burr after casting results in consumption of additional time and money and weakens and defaces the unit.
It is a general object of the instant invention to provide a locking clasp or locking means for a dental appliance which has none of the above-described disadvantages.
It is an object of the present invention to provide a locking clasp member for a locking clasp of a dental appliance, with which the locking clasp can be made with less time and labor than the current locking clasp.
It is also an object of the present invention to provide an improved locking clasp member which can be used to make a locking clasp in a dental appliance which does not require extensive reworking because of inaccurate casting procedures or misjudgments.
It is an additional object of the instant invention to provide an improved locking clasp member which is universally applicable for making a wide variety of comparatively strong dental locking clasps for both buccal and labial regions of the mouth.
It is another object of the present invention to provide an improved locking clasp member which can be used to make a locking clasp in a dental appliance which is more easily adjusted for wear than the current locking means.
It is still another object of the present invention to provide an improved locking clasp member which can make a locking clasp which can be used on a completed partial casting in need of altered or additional clasp retention.